Shooting Star Gakusaver (TV Miniseries)

OVA Mini-series (1993 - 1994). 6 Episodes. A gigantic meteorite landed on earth a few years back. A mysterious capsule believed to have belonged to the aliens was discovered. Called the "black box," an international organization called "Project BB" was created to research it. Eight boys, including Manabu Yoshimura, attend International Academy, end up getting getting inside the capsule. Then, a big spaceship appears in the sky and an alien calling himself Wercury appears in a 3-D image. He tells them he is from the Star of Prokimasi and that he has come to collect the meteorite of the Choshin people. If they do not hand it over, he will challenge the earth beings to a battle. Manabu and his friends are confused by the unexpected turn of events but the meteorite responds to the thoughts of the group and suddenly starts to transform itself into a gigantic robot. Then, attacked by the invading Prokimasi robot, they are forced to pull their strength together and fight back. (Source: MyAnimeList)